Adaptive place-pitch ranking procedure for optimizing performance of a multi-channel neural stimulator

Abstract

An adaptive place-pitch ranking procedure for use with a cochlear implant or other neural stimulation system provides a systematic method for quantifying the magnitude and direction of errors along the place-pitch continuum. The method may be conducted and completed in a relatively short period of time. In use, the implant user or listener is asked to rank the percepts obtained after a sequential presentation of monopolar stimulation pulses are applied to a selected spatially-defined electrode pair. Should the patient's judgment of pitch order be correct for all applied interrogations, then no further testing involving the tested electrode pair (two electrode contacts) is undertaken. However, should there be errors in the place-pitch ranking, which errors evidence perceptual place-confusions, then a search is undertaken for the spread of the perceptual confusion by separating the target channel and competing channel by one electrode contact at a time. This search for the spread of confusion continues until no errors are made in all directions. Identified channels wherein pitch confusion exists may be deselected (not used) during normal operation of the cochlear implant.

Description

[0001]The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 464,222, filed Apr. 18, 2003, which application is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to neural stimulators, e.g., cochlear implants, and more particularly to a technique for optimizing the number of channels a cochlear or other neural implant system should employ in order to enhance the performance of the implant system. In the case of a cochlear implant system, the present invention optimizes the number of channels the cochlear implant should use in order to enhance a user's ability to perceive and understand sound.[0003]Electrical stimulation of predetermined locations within the cochlea of the human ear through an intra-cochlear electrode array is described, e.g., in U.S. Pat. No. 4,400,590. The electrode array shown in the '590 patent comprises a plurality of exposed electrode pairs spaced along and imbedded in a resili...

AI Technical Summary

Benefits of technology

[0014]The present invention addresses the above and other needs by providing an adaptive place-pitch ranking procedure for use within a cochlear implant system. Advantageously, such adaptive place-pitch ranking procedure provides a systematic method for quantifying the magnitude and direction of errors along the place-pitch continuum. Moreover, the invention is clinically feasible, i.e., the procedure may be conducted and completed in a relatively short period of time.

Problems solved by technology

As the art of cochlear stimulation has advanced to produce bionic ear implants, the implanted portion of the cochlear stimulation system, and the externally wearable processor (or speech processor) have become increasingly complicated and sophisticated.

As the complexity of the bionic ear implants has increased, the amount of control and discretion exercisable by an audiologist in selecting the modes and methods of operation of the cochlear stimulation system has also increased dramatically.

For example, it is no longer possible to fully control and customize the operation of the cochlear stimulation system through the use of, for example, switches located on the speech processor.

While this may allow for the allocation of spectral details to be transmitted to the auditory nerve along a large number of physical channels, problems such as spatial channel interaction and the inability to resolve place of stimulation among adjacent channels may actually lead to poorer discrimination.

That is, systematic assessment of phoneme recognition by cochlear implant users has shown that while the features of manner of articulation and voicing are well transmitted, place cues are less well resolved.

As a result, it has been determined that having a greater number of stimulation channels by itself is not always sufficient to provide improved understanding.

To the contrary, in some instances, increasing the number of channels has actually caused a decrease in the user's understanding.

While assessing spatial (as well as temporal) channel interaction could be helpful in optimizing channels to be used in a stimulation sequence, the procedures necessary to carry out such assessment are far too cumbersome to be used clinically.

While clinical procedures do exist for “rating” (same / different task), “ranking” (high / low) or “scaling (numerical estimation) the pitch perceived by stimulating channels along an electrode array, such procedures do not provide a systematic method for quantifying the magnitude and direction of errors along the place-pitch continuum.

Without such a method or technique, the reduction or re-ordering of stimulation channels may only be accomplished in a haphazard way, thereby penalizing patient performance.

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